This invention relates generally to luminaire circuitry, and more specifically to a conversion circuit that may be incorporated into an existing lighting fixture for changing the type of light rendered operational by the same while substantially effecting a reduction in the energy consumed during the converted lamp's performance.
During the 1950's, communities became more concerned with enhancing the illumination of their streets during the evening and night hours, such mainly being necessitated due to the significant rise in the percentage of crimes perpetrated after dark. In addition, the safety of the pedestrian was foremost in such community action, and to attain some enhanced lighting, the usual type of incandescent bulb employed prior to said time was replaced by the rather improved mercury type vapor lamp that had come into production. Many of these series circuit operated vapor lamps are still in existence and in operation in the various municipalities.
Today's expense of converting a series primary loop to a parallel circuit and the installation of new ballasts to accompany the new and more energy efficient HPS lights is cost prohibitive for most municipalities. This converter invention was developed as a low cost alternative for retrofitting in the field with existing series luminaires and yields, as the embodiment of this application will show, benefits of energy economics comparable to new fixtures with the same HPS lamps are presently marketed.
As is known, the sodium vapor lamp is an arc discharge type of device having a gas confined to an arc tube surrounded by a glass envelope which produces illumination in response to electric potential and current through the ionizing gas contained within the said tube. Ionization must be initially brought about in order for illumination to commence. In addition, and by way of example, the mercury lamp type circuit for each light usually employs a 400 watt series ballast in its operation, and after it has been operating for some time, it consumes a driving voltage of 132 volts ac at 3.2 amps of current. Hence, the wattage or power consumed for operation of this type of lamp, in this example, is somewhere in the vicinity of 400-425 watts. This is a rather high wattage consumption for the circuit, and during this day and age, energy conservation has now become a necessity, and means must be provided for reducing the needless use of energy where such can be accomplished.
The current invention achieves by way of conversion of such earlier circuitry to one that can accommodate the lesser energy consuming high pressure type sodium lamp that utilizes much less wattage in its operation, frequently as much as forty percent or more for a lamp that can produce the equivalent foot-candles of illumination.
Various prior art patented circuitries have been available for furnishing illumination for such a lamp, but in most of these instances, they are circuitry that is for use in the original equipment market for initial installation and for accommodating lamps such as the high intensity discharge lamp, but which circuitry cannot function as a conversion means for replacing any earlier style less efficiently operating lamp of the type previously analyzed. Three such prior art devices are shown in the U.S. patent to Owens, et al., U.S. Pat. No. 4,037,148, and the two U.S. patents to Soileau, U.S. Pat. Nos. 4,092,564 and 4,069,442. These types of circuitry have generally been devised for meeting the starting and operating requirements for high pressure sodium lamps in an economical manner, and various electronic circuits are shown in the same but which have been proposed for parallel primary circuitry only. These devices work in combination with parallel ballasts of either the transformer type or the reactor type to generate the required operating current and voltage. And, further by way of reference, the aforesaid Owens patent discloses the use of a ballast controlled circuit which incorporates a triac and a triggering circuit and for use for regulating the power supply to a high intensity discharge lamp, but, as can be seen from reviewing its Triac circuitry, and its trigger circuit, the identified electronic components are much more complex for regulating their power supply output for the type of lamp being illuminated, and in addition, are for use principally for parallel primary circuits only. Also, it would appear that the electronic controls as set forth in this prior art disclosure are more for providing ballast control, as its name indicates, rather than acting as a particular converter for use in changing the current and voltage output from a series connected luminaire ballast that previously energized the high energy consuming mercury vapor type lamp to one that may now accommodate the high intensity discharge type of lamp, such as the high pressure sodium device.
Somewhat equivalent to the foregoing prior type of ballast control circuitry is also shown in the two patents to Soileau, as previously identified, wherein the provided circuitry furnishes operation for the high pressure sodium type lamp, but its power supply is already capable of producing a direct current source, that applies the dc pulses to its lamp, rather than disclosing circuitry that is for use for conversion purposes, and that is for rectifying the alternating current output of the secondary of the ballast to a direct current charge that can operate such a high pressure sodium type lamp. To obtain such, the Soileau circuitry incorporates the usage of an SCR switch which charges the capacitor of the circuitry for obtaining a positive voltage substantially higher than the supply voltage of the circuitry, and thus, with this higher supply voltage there is attained an improved color property for the operating lamp's output. Hence, these Soileau patented devices are not designed for attaining circuitry conversion.
The U.S. patent to Bodine, U.S. Pat. No. 3,889,152, discloses an apparatus for operating a high pressure sodium lamp, but the circuitry described requires a neutral conductor in order to attain its functioning. In addition, this Bodine apparatus must operate in a circuit that is parallel with its illuminated lamp, while the current invention is intended to operate only with the series connected type of lamps. Essentially, it would appear that this prior art device is designed for providing a much higher starting voltage from a lamp ballast for igniting high intensity arc discharge lamps in the category of mercury lamps, sodium vapor lamps, and the like, and that it is primarily for use in parallel circuits, without necessitating the need for any rectification of its ballast produced secondary charge that needs conversion for operating the current type high pressure sodium lamp from the earlier installed series connected mercury vapor type circuitry. Various other prior art patents also disclose related type of circuitry, with the patent to Elms, U.S. Pat. No. 4,162,428, disclosing a variable inductance ballast apparatus for a high intensity discharge lamp, but not containing a circuitry that is in any way equivalent to that set forth in the current invention. In addition, the patent to Powell, U.S. Pat. No. 3,193,726, discloses an apparatus for operating electric discharge lamps that includes an impedance simulator.
In view of the foregoing, it would appear most pertinent that the principal object of the current invention is to provide means for conversion of the previously installed series connected luminaire circuitry to produce a pulsed direct current output that may operate the lesser energy consuming high intensity discharge lamps currently available upon the market.
Another object of this invention is to provide a rather compact size converter that may be conveniently inserted into the secondary output of the light's ballast for operating the high pressure sodium type lamp.
Still another object of this invention is to provide a converter unit that may be fabricated into a compact arrangement and encapsulated for immediate and facile insertion within existing lighting circuitry.
Still another object of this invention is to provide a converter means for substantially reducing the energy consumed, in kilowatt-hours per year, by a community for attaining effective street lighting.
Yet a further object of this invention is to provide a direct current pulse for igniting and sustaining the operations of a high pressure sodium lamp.
These and other objects will become more apparent to those skilled in the art upon reviewing this summary of this invention, and upon undertaking a study of the description of its preferred embodiment, in view of the drawings.